Method for making alumina hydrosols



Oct. 20, 1953 E. A. HUNTER ETAL METHOD FOR MAKING ALUMINA HYDROSOLS Filed March 6, 1951 Patented Oct. 20, 1953 METHOD FOR MAKING ALUMINA HYDROSOLS.

Edward A. Hunter and Charles N. Kimberlin, Jr., Baton Rouge, La., assignors to Standard Oil Development Company, a corporation of Delaware Application March 6, 1951, Serial No. 214,158

9 Claims.

This invention relates to an improved method for making alumina sols.

While there are suggestions in the prior art of methods of making alumina sols or hydrosols, there are no entirely satisfactory commercial processes for making alumina sols or hydrosols on a large scale. One process generally referred to is the Patrick process wherein aluminum metal is reacted with acetic acid but the process is expensive because reaction proceeds very slowly. This process has been improved considerably by conducting the reaction in the presence of an oxidizing gas, but even with this improvement the reaction proceeds more slowly than desired.

According to the present invention, aluminum metal is dissolved in a water insoluble alcohol such as amyl alcohol or a higher aliphatic alcohol or a mixture of such alcohols. Instead of using the alcohol alone it is preferred to use a mixture of alcohol and a hydrocarbon or a hydrocarbon oil. The reason for using a water insoluble alcohol or alcohol-oil mixture is that the alcohol or alcohol-hydrocarbon mixture can be easily recovered and re-used to make an economical process. While the water insoluble alcohols are preferred, water soluble alcohols may be used in which event the recovery of the alcohol involves a more expensive distillation step. It has been heretofore known to hydrolyze an aluminum alcoholate made from a water insoluble alcohol but such hydrolysis results in a slurry of alumina in water.

According to the present invention an alumina sol or hydrosol is produced from a solution of aluminum alcoholate dissolved in excess alcohol or alcohol-hydrocarbon mixture by mixing therewith a peptizing agent such as an organic acid to obtain a substantially anhydrous homogeneous solution containing aluminum alcoholate and said peptiZing agent and contacting said solution with water to hydrolyze the aluminum alcoholate, and regenerate the alcohol leaving an alumina hydrosol as an aqueous phase. The alcohol is recovered and used in another reaction step for making more aluminum alcoholate. The alumina hydrosol is preferably digested or aged to improveits characteristics. The alumina sol or hydrosol produced is a stable one and may be used as such to form alumina gels or may be mixed with silica sols or various other forms of catalytic materials to make conversion catalysts having any desired content of alumina.

In the drawing:

The figure represents one form of apparatus for carrying out the process of the invention.

Referring now to the drawing the reference character l0 designates a reactor into which aluminum metal in the form of chips, turnings or the like is introduced through line I2. A catalyst such as mercury salts, mercury, iodine and aluminum halide or the like with mercuric chloride being preferred is introduced into vessel It] through line It. The alcohol or alcoholhydrocarbon mixture is introduced into vessel 89 through line l6. The alcohol is an aliphatic alcohol which is preferably insoluble in water or substantially insoluble in water such as amyl alcohol or higher alcohols or mixtures of such insoluble alcohols. The alcohols employed in the process must be essentially anhydrous. The aliphatic alcohols having 5 or more carbon atoms per molecule are especially useful in the present invention and the higher aliphatic alcohols are suitable provided they are insoluble in water and are liquid at the temperature of operation of the process.

While the water insoluble alcohol or mixtures thereof with other alcohols may alone be used to produce aluminum alcoholates according to this process, it is preferred to add to the alcohol a hydrocarbon such as heptane, octane, benzene, toluene, xylene, methylcyclohexene, or mixtures such as a petroleum distillate boiling within the range of 180 to 500 F. It is preferred to use a petroleum distillate of relatively narrow boiling range which boiling range includes the boiling range of the alcohol employed; for example, for use with amyl alcohols a petroleum distillate boiling in the range of 220 to 290 F. is satisfactory.

The addition of the hydrocarbon facilitates the separation of the alcohol from the water. In addition the hydrocarbon diluent aids in controlling the temperature during the reaction and also serves as a solvent for the aluminum alcoholate formed. The mixture preferably contains about 50% of the alcohol and about 50% of the hydrocarbon by volume but the hydrocarbon may range from 0% to 90% of the total volume.

To initiate the reaction, heat is supplied to vessel ill by a steam coil !8 or other heating means to heat the contents of vessel it to about to 300 F. During the reaction hydrogen is given off and this is vented through line 22 and may be recovered because it is pure hydrogen. After the reaction is well started it proceeds at a fast rate and generally cooling will be necessary. The cooling may be done by passing a cool ing medium through the coil H3 or other methods of cooling may be used. In a batch-wise type of operation the reaction is continued until the aluminum has gone into solution or for about 30 to 60 minutes.

The reaction may also be carried out in a continuous manner in which it is preferred to maintain at all times a large excess of aluminum metal in reactor t0 and to introduce; catalyst through line l4 and alcohol or alcohol-hydrocarbon mike ture through line [6 and to withdraw aluminum alcoholate solution through line 23 at a rate which-1 will provide sufiicient residence time. tor the cohol in reactor [0 for convertingthealcohol; to: 4 aluminum alcoholate to a desirable degree, an average residence time of about iiflrtoi .60; minutes. is desirable. Although reactor l llimay bemain tained at substantially atmosphericpressux e; ill-1:5- may be desirable to maintain reactor i0 under superatmospheric pressure such and to; 190, lbs per sq. in. gauge, preferabl about lbs. per sq in. gauge, in order to increase the boil iiig 'temperature of the reaction mixture. The reaction 2 of: the aluminum with. the. alcohol: is; carried; out. at a. temperature of about, 180? to. 300?- prefer: ab yab 1it.24Dfinc-210 .Ihe: reaction. pro uc comprisin a: solutio f aluminum alc hola c n hydrocar on; and excess. 25 alcohol.- ere withdrawn. from-tank lo throughiine; iens m xe with. a; mall mo nt f organic acid; or. the peptiains. aeentsuch. acetic acid tefie ab y lac al. acetic. acid. add d throuehli-ne 3 Usu lly abou than Qt ce ic-acid Pl'3.p3J-T $:Qf-; alum na y. we t. calculated. A1293 cone. tamed. n he. a coholate solu on. sed; bu atioa ary be wee L of ace icac d to 1.0; 0. alumina an Z-of; ac t cacid o; oial m na 3'5 he. nt odu ti n; of ac al- Q1: nh dr us, acetic, c d throu h inev Homic des su stant lly an.- hydrous. h m eneo s. solu ion. Qt uminuml air. coh lete and. ac ti aci n); ex ss; alc hol; hydrocarbon, which solution upon hydrolysis; 4 with resently obedes ribed, will produ a l aqueous thes comnr s' alumina oh or. hydr so Allthe seni i fiil'fli i ir 19 1 hereof. bea dedi a nce b o s-end n 2 4 5; alternatively, apart, of the, atifi fia acid: may. e asideiiw thi tcnini heh dr l t p r s:-

b di. HQWQVQ B. t c eierreda o add at east; nehahr h ce ic cid h ou h. i 52. l rr ha no iioa f; eaoeticac siad d;

.j h ih rol sis: atera helslaci tac ti e d 50. adva e Q en he other. crazi st.

Wh leieQeiic-Mis a liei eiens n w s. a nt, other pep zine; a en s. ch: as; for. acid, propionic acid, glycolic acid, lactic ac ar aric. ac d; hydro en. hloride. hydrogen=.b1-o as. mid ,.a1um num chloride, a um num hromideand; the l ke; may. oca ised- A-fter. the. addition; of the. acetic acida: fromlines 24;. themixtlire is -.passe d through line 2 51. and an. orifice. mixer. 2.6.; Where, the i alcoholateand; acid. 601 aremixed. The; solution of;a1uminum alcoholate-v containing; acetic;v acid: 1eaving.,m i xing.'zone; 2553 by line; 2-']'-i is admixed: with. water introducedgbyi line. 325. If; desired; a. further amount; of the acetic acid: is introduced: withthe wat'en by line: 28.; The; resulting mixture v.is.passed rthrough; an orifice .mixer 3 3:.which functions as a. hydrolysis. and peptizing. zone. where the; mixtura is-t vigor ouslyeagitated. The. amount: of:-water. may-vary. betweenabout 1;.to; 9.9..parts by weightzofealumina. toawater and 6 to 9.4 1partsby -w eight-. on alumina. to water; Instead of using. orifice. mixers 26.: and. 34, other forms. ofmixing m'eansim'ay be used. to.- obtain the. desired. agitation; In mixer.- 34;;the.-.alcoholate..is.hydrolyzed to: .regeneratezthes 4 alcohol and to form an aqueous phase comprising alumina hydrosol. The temperature in the hydrolysis zone 34 may be within the range of 60 to 220 F., preferably about to 200 F.

From the second mixer 34 the mixture is passed through line 3,6- to. a settling; zone 35;, which may be providedi witlt a steam heat coil 42 or other heating means to heat the contents of zone 38, desired, to about 70 to 210 F., preferably 150 to, 200 The mixture may be maintained in zone? 38ata' temperature between about 150 and 200 F. for 30 minutes to 5 hours to provide an aging or digestingv period for the alumina sol. In settlingzoneBE-the aqueous and organic phases separate with theorganic phase forming the top layer which is conducted overhead through line {$1,159. a dewate ring or distillation tower 12 later to be described.

The lower layer comprising acetic acid stabilized alumina hydrosol and residual organic solvents is withdrawn from the lower portion of settling zone 38 through.- line, 458.; and passed to; the. distillation tower 46. In distillation. tower 46. the. aqueous: phase. comprising a, stable; alumina hydrosol is. stripped of residualalcohol; and. hydrocarbons. The alumina hydrosol; con;- tains. about. 1%, to. 81%. by wei ht alumina and: about..0.1;% to 1Q.% by. weight ofL acetic acid; The; le min ydro ol. is W thdrawn from he.

0 bottom of; tower 46; through line 52 and' may be;

stored as such or may be usedfor the; preparation of alumina, geliparticles in any desired form; or shape or, it may. he-miXedWitH-Bi ica yd o c s or hydr els. to. m ke. hy o ar on. c ny nsiont catalysts ranging; from- 1 to, 99% by. weight of alumina with the rest; being silica. If desired alumina hydr so rQmJ i lmay be intr du ede y in 52a; into. in t k. 5.1 p ovided. wi h. h a in m ans; 529. w r h lumina-, yd may beased or /2. 9. .0.: 1 r t a tempera u e: of 150? to 21 E; Agedhydrosolis withdrawn from; aging tank; 52b; by line; 52d. and may be: stored as. such; or; usedg for. the preparation, of. alumin eei ar icles.- ata ysts...

Heat supplied to the tower 46 bysteam heat ing coil 54; or, other suitbale. heating means, to. heat the;contents,thereof to aboutzlzf Int the; distillation tower; 46 the-residual: water, in soluble; lt holrh droc rbon xture o e. a-.-= terandzsomeiaceti acid;a eparat d ndpa scd, overhe d hrou h i 5. av s-cv ondenser. 58,. The: condensed. mater al. snassed: to earato B2:- to separate a lower. Wate 1 y r.-- ontaining a'.'.-.smal1 amountn fg ceti cidz r m. a erli soluble uppe ayen ontain n z he lcoh l hy r ca'rbon mixture. Thewa n la LW tIhdl'aWD-v from. the bottom .of; senatrator; 62;; through line 1- 6,4 and. returned eithen; to; distillation tower; 46-; or? returned;to.line,32;.thr0u h;-line 5,5; to the -h5 drolysis estep.

e npenwater insolub e; ayer s; vii drairni through: line v .66; and mas d. brp mnfitzto-ai o watering or dryingtower 'i23proyided1with5a; steam. heatingv coil. 76. or; other: heat-ins Sr. Theid-rying: still is=heated-togabout lfliii: 01300? to I separate water from; the: water: insoluble a fcohol-hydrocarbon-i mixturet. Wate -N nci": 0Q taining. some: alcoholand: hydrocarbon. with; t"; p s s: v rheadathrough .linjezl ttproyidediwitmaa condensenfl'mfor. condensing-i the5=vap0rs and-:zthe condensate is passed into settlingrand separating; tank 82 where gravity separatiomtakes; placej to forma bottom .waterelayerriiil andga'itop; alcoholhydrocarb'on layer. 8.6;; The-.watergiswithdrawnfrom .thexwater layer; andzpassed,throushalincefi by pump 92 into line 32 for reuse in the hy-- drolysis step. In this way any alcohol and/or hydrocarbon mixed with the water is returnedto the system and not lost. The alcohol-hydrocarbon layer is withdrawn through line 95 and returned to the drying still 12 for further drying. The alcohol-hydrocarbon mixture which has been substantially completely freed of any dissolved or entrained water is withdrawn from the bottom of drying still '52 through line 90 for return to line It and vessel l for reuse in the process.

The following examples are given merely as illustrative of the invention and the scope of the invention is not to be restricted thereto as changes and modifications may be made without departing from the spirit of the invention.

Example I About 864 gm. of aluminum turnings were dissolved in about 32 liters of a 50-50% by volume mixture of an anhydrous C alcohol mixture and a hydrocarbon oil and containing about 6 grains HgClz. The C5 alcohol mixture contained isomeric amyl alcohols so that the alcoholate formed was amyl alcoholate. The hydrocarbon oil was a distillate having a boiling range of about 200 to 400 F. The reaction was carried out at a temperature of about 270 F. until all the aluminum metal was dissolved and 1 cc. of the solution was equivalent to about 0.05 alumina.

About cc. of glacial acetic acid was then mixed with agitation to about 600 cc. of the alcoholate solution. The agitation was done by a propeller type agitator in a beaker. The ratio of acetic acid to alumina was about 1 to 3 by weight. The mixture was then added rapidly with the same type of agitation to 1000 cc. of 1% acetic acid at about 180 F. and the agitation was continued for about 5 minutes after which the agitation was stopped and the mixture settled until a major portion of the alcohol-hydrocarbon mixture separated as an upper layer. The upper layer of alcohol-hydrocarbon mixture was ale-- canted. The remaining lower aqueous layer was digested with slow boiling for about 30 minutes at about 212 F. and yielded a translucent stable alumina hydrosol containing about 3% alumina and about 2% acetic acid.

Example II About 864 gm. of aluminum turnings plus about 0.5 gm. HgClz were dissolved in about 32 liters of a 50-50% by volume mixture of a hydrocarbon fraction and anhydrous Pentasol. The Pentasol was a mixture of isomeric C5 aliphatic alcohols. The hydrocarbon fraction was a distillate having a boiling range of about 200 to 400 F. The resulting amyl alcoholate solution was hydrolyzed with a solution of about 520 cc. of glacial acetic acid in about 55 liters of water (about 1% acetic acid by weight) at 175 F.

The hydrolysis was carried out by pumping the two solutions in controlled ratio of about 55 parts by volume of acetic acid solution to 32 parts by volume of the alcoholate solution, the two components being discharged simultaneously on the impeller of a centrifugal pump to produce rapid mixing. The mixture was discharged to a large separatory funnel where it rapidly broke to an upper organic liquid layer and a lower aqueous layer comprising a milky alumina hydrosol.

The alumina hydrosol was then charged to a still pot and refluxed under a still-head which returns the aqueous overhead to the pot, while the organic overhead was removed and added to the alcohol hydrocarbon fraction previously recovered to be recycled to the aluminum alcoholate preparation step. During this treatment the temperature was maintained at about 212 F. for about 30 minutes. The still bottoms comprised an alumina hydrosol of excellent translucent appearance with no evidence of sediment or settling.

Example III About 27 grams of alumina turnings plus about 0.1 gram of mercuric chloride plus about 0.1 gram of iodine were dissolved in 600 cc. of anhydrous isopropyl alcohol. The mixture was heated under reflux to initiate the reaction, but after the reaction was well started it wa necessary to provide cooling and finally the mixture was again heated under reflux to complete the reaction. About 1 /2 hours were required to complete the reaction between the aluminum and the isopropyl alcohol. After completion of the reaction about 5 cc. of glacial acetic acid was added to the solution of aluminum isopropylate in excess isopropyl alcohol and immediately thereafter the solution was added with vigorous agitation to 2000 cc. of water which had been heated to 150 F. There was formed an alumina sol. The isopropyl alcohol was distilled overhead from the alumina sol leaving a bottoms comprising an alumina hydrosol of about 3% concentration. The recovered isopropyl alcohol may be dehydrated for reuse in converting more aluminum metal to aluminum isopropylate.

When producing a silica-alumina catalyst containing from 10% to by weight of alumina with the rest being silica by selecting the proper proportions of the alumina hydrosol prepared as above described and a pure silica hydrosol prepared from a dilute solution of sodium silicate by passing the sodium silicate solution over an acid regenerated cation exchange bed of material such as a resin it is also preferred to age or digest the silica hydrosol so produced.

The silica hydrosol may be prepared by contacting a dilute solution of sodium silicate for example the Na2O-3.25SiO2 with the solution containing about 20 to 50 gm. S102 per liter, over an acid regenerated cation exchange resin to produce a silica hydrosol containing about 3% by weight of silica but the range of silica may range from about 2 to 5% by weight. The DH of the silica hydrosol is within the range of 2 to 8. Before mixing the silica hydrosol with the aged alumina hydrosol above described, it is desirable also to age or digest the silica hydrosol so that it time of setting is decreased and also the silica hydrosol is more highly polymerized before the hydrosols are mixed. For this purpose the silica hydrosol is passed to a digesting or agin zone provided with heating means for heating the silica hydrosol to a temperature of about to 200 F. and maintaining the silica hydrosol at this temperature for about 30 minutes to 5 hours. The aged silica hydrosol at a temperature of about 70 to 200 F. is then thoroughly mixed with the desired amount of alumina hydrosol at a temperature of about 70 to 200 F. to produce silica alumina gel particles in the desired form and the gel is then dried. By spray drying the mixed hydrosols or passing them as droplets into a heated oil bath, microspherical gel catalysts are obtained.

What is claimed is:

l. A method for preparing alumina hydrosols from anhydrous aluminum alcoholates which mixture: to hydrolyze. the aicoholate; andiregenere ate: the aicohoh at. a; temperature; between; about; 60? 2201? F; v andasepaizating' al'umiha hydrosol; from theemixtimez A'. methmi the: preparation: at alumina: whicln comprises: mixing: an anhydroue aluminum; alcohnlatei derimedi from; an: alcohol haying: 2: to: 1D) canbam atoms? per molecule with glaciaii acetic: a.cid,. then: adding an additional amount: of; aiaciali. acetic; acid; and: water: to: the

firsti-mentionedimixture; and; agitating to i hydro;

the: alcoholate" and; peptize; the; aiuminag. dizgesting the; peptizeda and hydrolyzed mixtures for amextendedi periods of time at anselevatedz perature; amt. then separating a: stable: alumina-' hydroselifromithe digestedimixture;

4: Aamethodiaccording'; to claim; 3: wherein\ the:

amonntioft-aceticsacid usedzisawithinlthezrangefof about 1 part by weight of acid to 1.0:partsiby" weight: ofiaiuminaiand- 2: parts of: acid;by weight moved= By a distillation step i'e'avihg the aihhiha hydrosol.

'1. A- method or preparing" hydrosoie which comprises adding first a substantiallj an? hydrous acetic acid as a; peptizing agent and later anaqueous hydrolyzing agent to an anhy drous aluminum alcoh'olate; heating to' a teniperature-within the rangeof about 150 t0200 while hydrol'yzing, agitating the mixture to obtaiir intimate contact between the acid and the-alumii1um= alcoholate and between the water and the aluminumaicoholat'e to hydrolyze" the aluminum" alcohdlate; heating the resulting. IiiiX-"j ture and separating a stable alii'min'a iiyar'os'or from the mixturet s. A method" of preparing alumina hydrosols which comprises adding; a substantially anhydrous acetic acid as apeptizing agent to an anhydrous aluminum alcoholate, hydrolyz'ing the ammmum; alo'oliolajte' at a" temperature hetvireeii 60 and' 220" F; to form pepti'z'ed hydrous a1u"- mine, heating the resulting mixture and separating a stable alumina hydrosol from the mix time:

9; A- method of preparing alumina solwhich comprises" addin'gan anhydrous acetic acid as a peptizing agent to an aluminum alcoholate' of a substantially water insoluble aliphatic alcohol before contacting withwater and thereafter-11y ao drol'yzing the aluminum alcohola'te by mixing" toeLpanta by, weight offalumina, and whereimthe:

amonntioizwatenused isswithi'n themangeuofabout 1 :nartz: of: aluminazbyiweightitoz 995 parts a of: water: byweightz and; 6; partszoix alumina by weight to 9 izpartsioi'zwaten-by'weighta 5:; memethodzaccordingsto; claim; 3; wherein-ethe digestiomtemperaturesisrw-ithin tharangeof: 150.? M52002 Exandzthe period:0fr.time:is:about:30 min utes to 5 hours.

- 62-;A methodzaccordingato claim 3:.whereimtlie alcohol; azawaterr insoluble/- alcohol and: isl re with water containing a; pepti'zingf agent at a temperature" between about and' 22'0 F. and recovering'an aluminas'o l; I w

D A DiA U T R CHARLESN. KIMBERLIN, JRi

References cited in the file of this" patent UNIT-E13 STATES PATENTS 

2. A METHOD FOR PREPARING ALUMINA HYDROSOLS WHICH COMPRISES MIXING ANHYDROUS ALUMINUM ALCOHOLATE WITH AN ANHYDROUS PEPTIZING AGENTT, SELECTED FROM THE GROUP WHICH CONSISTS OF ACETIC ACID, FORMIC ACID, PROPIONIC ACID, GLYCOLIC ACID, LACTIC ACID, TERTARTIC ACID, HYDROGEN CHLORIDE HYDROGEN BROMIDE, ALUMINUM CHLORIDE AND ALUMINUM BROMIDE, ADDING WATER TO THE RESULTING MIXTURE TO HYDROLYZE THE ALCOHOLATE AND REGENERATE THE ALCOHOL AT A TEMPERATURE BETWEEN ABOUT 60* AND 200* F. AND SEPARATING ALUMINA HYDROSOL FROM THE MIXTURE. 